“Live Loads are variables, unpredictable and mobile such as people, furniture, snow, rain and ice. Live loads can vary at any given moment. Live Loads are expressed in Pounds per square feet.”
Definition from the Book: Structure for Architects, An Introduction Primer
Live loads can also be expressed in kips per square foot. A kip equals 1,000 pounds. Good definition with a citation! Can I ask for a page number too?